This research program in developmental phonological disorders has the long term objectives of description, explanation, prediction, management, and prevention. The current proposal includes 10 study areas to enhance and test a research model that has guided methodologic and substantive studies since 1980. The model divides relevant independent and dependent variables in developmental phonological disorders into three primary domains, Speech Status, Causal Status, and Management Status. The goal of the current proposal is to conduct three tests of a predictive hypothesis about speech normalization following indirect (caregiver-based) and direct (clinician-based) management. The predictive hypothesis is that of 15 putative subdomains within Speech Status, a speech-delayed child's Metalinguistic Status, which subsumes three constructs -- Metaphonological Status, Motivational Status, and Stimulability--predicts the most significant portion of variance in speech normalization. In Year I, a total of five studies will enhance methods and provide substantive information from a database of children with speech delays of known and unknown origin. In Year II, a total of four studies will yield procedures and information for remaining methodological needs, including prospective data on prediction from two longitudinal data sets. In Year III the predictive hypothesis will be tested in 18 prospective, single-subject intervention designs. Six of the studies will use the unique minicomputer database containing over 1200 comprehensive speech records and diagnostic information (over 4,700 fields per file) from 383 subjects with speech delays of known and unknown origin. Findings from this proposal are expected to impact currently unresolved service delivery questions for the 2.5% of preschool children identified as having speech disorders of heretofore unknown origin. The immediate goal is to isolate and explicate processes underlying normalization with and without intervention. Long term aims are focused on primary, secondary, and tertiary forms of prevention (Asha, 1982; 1987).